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302 ford eng. do you need a pcv valve

Discussion in 'The Hokey Ass Message Board' started by OldBlueOval, Sep 4, 2011.

  1. OldBlueOval
    Joined: Jan 10, 2006
    Posts: 197

    OldBlueOval
    Member
    from Upstate NY

    Got my 302 finally running!! after many set backs ,I have a set of ford motor sport finned valve covers , both sides are open and I can install vent style twist caps on them. Do I need to install a pvc vent to the air cleaner? Running a elect fan but motor seams a little hot to me. Need to figure out a few things yet ran it around the block a few times and it quit?? but started up after it sat a while any ideas what to check? It's a 1978 302 with a c4 transmission elderbrock carb. new style dist with built coil.
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 26,414

    squirrel
    Member

    You might want to run a pcv valve from one valve cover to the intake manifold or base of the carb (wherever there's a 3/8" vacuum hose fitting available), and you should be ok with an "open" style breather on the other side.
     
  3. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 7,393

    Don's Hot Rods
    Member
    from florida

    I bought a set of Edelbrock finned aluminum valve covers for the 331 in my 27 and then realized they had no provision for venting or even adding oil, so I added a pair of Moon breathers that have a removable top that allows me to add oil through them.

    I've run the car this way for a year now and it works fine. You will be ok with what you described.

    Don

    [​IMG]
     
  4. 65COMET
    Joined: Apr 10, 2007
    Posts: 2,847

    65COMET
    Member

    A pcv needs full vacuum,the air cleaner will not work.I made the mistake of not venting the crankcase on my 65 Comet 289,blew out the front seal.Run the pvc to a full time 3/8" vacuum port in the manifold or carb base,put on a filtered open breather on the other cover or a closed breather with a nipple for the hose that goes to the air cleaner.That is how an original closed crankcase setup was run.You NEED to vent the crankcase somehow!!A pcv does not effect performance,have ran 1/4 mile tests back to back,no change!! ROY.
     
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  5. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 9,049

    Jalopy Joker
    Member

    you can run just open breathers but, makes a mess after running a while. using PCV to carb base and breather tube to air cleaner base is the way to go. which ride is the 302 in? post pics for help with running hot problem.
     
  6. rustyfords
    Joined: Jun 17, 2008
    Posts: 1,123

    rustyfords
    BANNED
    from Location

    My 302 is out of an 88 Lincoln and had no provisions for a PCV in the valve covers.

    I'm adding a PCV to one of the valve covers that connects to the base of the carburetor and as described above, a small vacuum line from the breather in the other valve cover to the air cleaner.
     
  7. T.L.
    Joined: May 24, 2011
    Posts: 153

    T.L.
    Member
    from Colorado

    You don't have to run a PCV valve, but the crankcase DOES need to be ventilated. You can run open breathers as previously mentioned, but you might as well run a PCV valve, as it does not rob power, and actually makes the engine run better on the street. As previously mentioned, the PCV valve must be connected to full vacuum...
     
  8. Deuce Daddy Don
    Joined: Apr 27, 2008
    Posts: 3,451

    Deuce Daddy Don
    ALLIANCE MEMBER

    65 COMET is correct!!!---Lets everything breathe right!
     
  9. gimpyshotrods
    Joined: May 20, 2009
    Posts: 7,731

    gimpyshotrods
    Member

  10. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 7,393

    Don's Hot Rods
    Member
    from florida

    The pcv is simply an emissions device, the engine doesn't care how the vapors get out, just so they do. Remember when they had road draft tubes, pre pcv ? Some even only had round breathers on the valve covers, or on the oil fill tube. The Government was the one who mandated pcv's in the first place to clean up the air.

    The Moon breathers provide more than adequate venting and have baffles and foam inside to keep any oil from escaping..........no mist or drops on the car ever. If your rings are doing their job you will have very little crankcase pressure.

    Most boat inboard engines have no pcv valve, but simply tubes coming off the valve covers that go to the flame arrestor so any fumes are dumped back into the carb or fuel injection.

    Don
     
  11. Safari-Tracker
    Joined: Aug 10, 2011
    Posts: 13

    Safari-Tracker
    Member

    I have M/T valve covers with twist in breathers. I have more oil on them now, then i would like, were can i install a PCV on the 289.
     
  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 7,731

    gimpyshotrods
    Member

  13. Kripfink
    Joined: Sep 30, 2008
    Posts: 2,043

    Kripfink
    Member

    This is what we did on my 351w to keep it neat and tidy, if it's of any help to you.
    Best of luck
    Paul

    [​IMG]
     
  14. When I fitted a 'PCV' to my old Buick 215 it stopped the front crank seal dripping. :D

    Mine was home made, just a 3/8"vacuum hose from valve cover to carb, with a restrictor in with a 1/16"hole drilled in it. Worked a treat.
     
  15. tommy
    Joined: Mar 3, 2001
    Posts: 14,738

    tommy
    Member

    Yes you need a PCV system. Vents on top do not remove the water vapor that condenses inside an engine when it is shut off. If you ever worked on a neglected engine you would notice the chocolate milkshake shit inside the valve cover....a classic sign that the PCV system is not working. Air needs to move through an engine and not just vent at the top. A PCV system is just an enviornmentally friendly way of doing it. Before PCV systems the factories used road draft systems to get air flowing through the engine to extend the life of the engine and reduce sludge. I don't like sludge.
     
  16. More of a classic sign some dingbat removed the thermostat to help the motor stay cool, and it then never got up to operating temperature enough to evaporate off that water vapour.
     
  17. tommyd
    Joined: Dec 10, 2010
    Posts: 5,180

    tommyd
    ALLIANCE MEMBER
    from South Indy

    NICE, I'm seeing real hot rod engines! You know.....with the dizzy in the front, the way God intended:D
     
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 26,414

    squirrel
    Member

    PCV systems were optional for years before the gov't mandated them in the early 60s. If you're gonna trade in your car every two years, who cares? If you plan to put a lot of miles on it and have it last, you'll run PCV.
     
  19. havi
    Joined: Dec 30, 2008
    Posts: 1,869

    havi
    ALLIANCE MEMBER

    They had an interesting breather on powerblock tv a couple weeks ago, that was red in color, had a relief valve built inside, and installed on Keith Dorton engines. Whoever makes that, I'd be curious to know?

    These valve covers we see for sale with no provisions for PCV, are likely for older engines with road draft tubes. My 221 has that set-up, and though it looks period correct (for obvious reasons as it's stock) it does create a mess. But I do like the clean valve cover look. Hiding a PCV would be a viable option, IMO.

    Sometimes function over looks is the way to go, though.
     
  20. Shizzelbamsnapper
    Joined: May 13, 2010
    Posts: 317

    Shizzelbamsnapper
    Member
    from Ohio


    That would be because it was/is Fuel injected and the PVC is in the back of the intake and routes to a port under the intake. Still needs to breath through either a PVC or breather.
     
  21. Engine man
    Joined: Jan 30, 2011
    Posts: 1,954

    Engine man
    Member
    from Wisconsin

    My take on PCV systems is that there is air in your crankcase. No matter how good your rings are, there is an end gap so there is also some blow by putting more air in the crankcase. As the crankshaft spins around, the air will mix with the oil and create foam [bubbles]. Foamy oil is hard on bearings an can build up crankcase pressure. Foamy oil takes longer to run back down to the pan from the valve covers. Having a slight vacuum makes it harder for bubbles to form.

    Most racers have learned that PCV systems are a must to prevent high revving engines from blowing out oil.
     
  22. squirrel
    Joined: Sep 23, 2004
    Posts: 26,414

    squirrel
    Member

    Blowby isn't just air, it's mostly exhaust, which includes water vapor. Not good.
     
  23. Judd
    Joined: Feb 26, 2003
    Posts: 1,775

    Judd
    Member

    X2 My 351W blew oil all over with strait vent caps and used oil but works fine and uses no oil with stock style vent system.


     
  24. mustang6147
    Joined: Feb 26, 2010
    Posts: 1,848

    mustang6147
    Member
    from Kent, Ohio

    PCV system is needed as a result of crankcase pressure from pistons going up and down, and as a by product of ring blow by often used to determin the life of the engine.

    As the piston goes up it compresses gas air mixture, well as a piston moves down pressure is also created but at a lower psi, however crank case pressure will rob HP because there wil be resistants on the down stroke.

    Many auto mfg messed with vacuum pumps, and drag racers hook a 1/2 inch hose between their collectors and the valve covers. This creates a negative 3 to 4 psi vacuum in the crank case which is optimal for performance.

    The late 80s olds toronados had vacuum pumps to gain hp as well on the tofeo cars.

    Bottom line is, no a pvc valve isnt necessary however a sealed crankcase is a bad thing. I run a pcv valve on my street cars, and either connect the other side valve cover to the air cleaner or put a breather with a air cleaner on it, cuz air in must also be clean.
     
  25. OldBlueOval
    Joined: Jan 10, 2006
    Posts: 197

    OldBlueOval
    Member
    from Upstate NY

    Thanks for all the help and info!! Joe, Problem #2 I got the truck running but it seams to quit like it run out of gas?? and won't start back up right away it has a mechinal fuel when I take the line off the carb and run it to a pail I don,t get a lot of gas maybe 1/4 cup after turning it over quite a bit! When it's cold it will start right. maybe run4- 5 mins I got the timing close but quits ever time I want to put the timing light on. I'm Working by my self, Could I have the wrong fuel pump? the two lines off the pump I have the hose barb male end going to the tank and the threaded female going to the carb. I have not installed a fuel filter yet and I put 5 gallons of new gas in her. Letting the battery charge up a bit and back at it!!
     
  26. Engine man
    Joined: Jan 30, 2011
    Posts: 1,954

    Engine man
    Member
    from Wisconsin

    This would only be true with an odd number of cylinders. On a 4,6 or 8 cylinder engine, when one piston is going down, another is going up so the same volume of air is maintained and no compression occurs. Air does have to transfer from beneath one piston to another but the resistance is minimal.
     
  27. squirrel
    Joined: Sep 23, 2004
    Posts: 26,414

    squirrel
    Member

    Sounds like you have the pump connected properly. Could be a clogged line or pickup in the tank, or a leak in the line, or some other weird problem making it not get fuel. When you disconnect the line from the pump linlet, you should get a steady stream of fuel running out the line, if not then you need to fix the pickup or fuel line issue. Also make sure the tank is vented, older gas caps have a vent built in them.
     
  28. Willy301
    Joined: Nov 16, 2007
    Posts: 1,426

    Willy301
    Member

    For those who have said the VCs don't have provisions for but they would like to run a PCV, you can drill a hole at a high point in the side or back, making sure the PCV does not interfere with the rockers, and put in the rubber bushing and put it in. If you get a PCV with a 90 degree exit fitting, you can hide it in the back of the VC and nobody will be any the wiser.
     
  29. squirrel
    Joined: Sep 23, 2004
    Posts: 26,414

    squirrel
    Member

    You probably want to add a baffle so the valve won't draw oil
     
  30. Cerberus
    Joined: May 24, 2010
    Posts: 1,361

    Cerberus
    Member

    Positive Crankcase Ventilation (PCV) reduces sludge/ caking of oil that can build up in the lifter valley below the intake manifold when a PCV valve is not installed. Very fugly looking when you change out an intake manifold.
     

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